1. Field of the Invention
The invention relates to a method of tungsten film deposition and, more particularly, to a method of forming a tungsten film having good film morphology and low resistivity.
2. Description of the Background Art
In the manufacture of integrated circuits, tungsten (W) films are often used as contact metallization or plug metallization for aluminum (Al) interconnect schemes. Tungsten (W) films may also be used as a diffusion barrier for copper (Cu) metallization.
Tungsten layers are typically formed using chemical vapor deposition (CVD) techniques. For example, tungsten may be formed by thermally decomposing a tungsten-containing precursor. For example, W may be formed when tungsten hexafluoride (WF.sub.6) decomposes.
However, when tungsten films formed from the decomposition of WF.sub.6, are deposited on oxides (e.g., silicon dioxide (SiO.sub.2)) poor film morphology may occur. The morphology of a film refers to its thickness, film continuity, surface roughness, and grain structure. For example, tungsten films formed on silicon dioxide (SiO.sub.2) from the thermal decomposition of WF.sub.6 typically may have a discontinuous film morphology. Such discontinuous film morphology is undesirable because it may affect the electrical characteristics of the tungsten film increasing the resistivity thereof.
Therefore, a need exists in the art for a method of forming tungsten films having good film morphology and low resistivity.